Subtract 7/8 from 3/21, Solve 3/21

Subtract 7/8 from 3/21

3/21 - 7/8 is -41/56.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 8 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 21 × 8 = 168,
3/21 = 3 × 8/21 × 8 = 24/168
Likewise, for the 2nd fraction, since 8 × 21 = 168,
7/8 = 7 × 21/8 × 21 = 147/168
Subtract the two like fractions:
24/168 - 147/168 = 24 - 147/168 = -123/168
After reducing the fraction, the answer is -41/56

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